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DrVenkman last won the day on July 7 2019

DrVenkman had the most liked content!

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About DrVenkman

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    Back off, man! I'm a scientist.
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    "I love the smell of flux in the morning. Smells like ... continuity!"

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  1. I bought this little widget a few months ago and it works great for testing stuff out of circuit, including diodes, transistors and capacitors. https://www.amazon.com/gp/product/B08K3BGKXC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
  2. Yep. And on Thursday morning I basically said the same: Anyway, glad the issue is finally sorted.
  3. Now that you have the ANTIC issue straightened out, and you've already swapped the 4050 without result, the remaining color problems indicate an issue with either GTIA itself or its socket (the colorburst signal inputs or its LUM signal outputs) or the color trim pot as the next things to investigate. If you have at least a multimeter, with the trimpot turned all the way to one direction, measure the input and output voltages. Then turn it about half-way and measure again. Then turn it all the way and measure a third time. Those values will confirm that (a), the pot is getting the correct input voltage and (b), that it's generally working correctly, or not. If it appears that the color pot is working, and you are confident there are no issues with the GTIA socket, then you're down to the discrete components in the video circuitry, which can be a pain to diagnose. I'm not familiar with the PAL output circuitry, but if there are transistors involved, it seems to me that - being active components - are much more likely to fail than are resistors and ceramic caps.
  4. If you have a socketed spare machine, try the GTIA and ANTIC from this machine into a known-good, working machine. If they test out as good in another machine, check the sockets on this one for bad connections at the chip legs, cold solder joints to the PCB, solder flakes, etc.
  5. Yes. The handful of prototype and pre-production 1400XL’s actually have PBI ports on the back, and the case plastics to match.
  6. They’re all just re-purposed 2600/7800 shells so the only difference is whatever variation exists between the specific pieces of plastic in that particular example.
  7. Do you have a screw installed under the label?
  8. Dan’s pretty active on FB - you could contact him there and ask him directly if he remembers anything particular about it.
  9. I was not any kind of real programmer and lack the coding experience appreciate the nuances of his work, but I recognize the great contributions he made to the homebrew world and the AtariAge community as a whole. His untimely passing is a tragedy. My condolences to his friends and family.
  10. A US-market version of the ZX81 was my first home computer. I own two of them today and have spent a lot of hobby time this summer repairing and restoring them. RIP, Sir Clive.
  11. Just watch the SpaceX Inspiration4 launch tonight - the grin on Hayley Arcenaux's face during ascent was priceless. I am so excited to see non-government, non-professional astronauts getting a chance to fly, and doing it to raise money for a fantastic good cause.

  12. If your electronics guy is unfamiliar with the UAV in a 7800, be sure he knows that TIA color and MARIA color signals go into separate inputs on the UAV, and both must be present to get 7800 and 2600 games in color.
  13. No one’s suggesting it didn’t work - people are asking IF IT DID. That’s a subtle but significant difference, especially in light of the problems we know are inherent in the A8 bus design when you add additional capacitance and the attendant signal propagation delays that adding capacitance causes. Rather than handwaving away these legitimate questions, Michael asks the important question.
  14. Since this device would be connected directly to the bus, you would have to be VERY careful to avoid adding capacitance and screwing up bus timing. Fast modern devices like SIDE3 are already problematic in some machines due to timing issues - many reports of people having to replace the 74LS08’s in their systems with faster 74F08’s to improve the BPhi2 signal enough to allow those machines to boot. Adding a long cable and multiple cards may not work out in practice. Issues like this at the prototype stage may well be what got the project killed in the first place.
  15. Joystick directions are read by the RIOT chip, if I recall correctly. I’d verify the issue with some bare 2600 and 7800 carts (e.g., not a ROM loaded from the Concerto), then open up the console and verify continuity, voltages, etc. Pull the schematics and start checking for any failures or cracked/cold solder joints as well. If the console has been modded in the past, check for stray solder flakes that might cause an intermittent issue also.
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